In mobile communications systems, there are cases where relay stations each of which wirelessly relays signals between a wireless base transceiver station and a mobile station are employed. For example, as countermeasures against dead zones, relay stations based on an RF (radio frequency) direct amplification method (also referred to as an amplify-and-forward (AF) scheme) have been put into practical use. Dead zones, in which relay stations of this type are installed, include, for example, cell edges, dense areas within each cell, underground malls, and tunnels.
Regarding a method for establishing connection between a communications apparatus and a base transceiver station by multi-hop method, there have hitherto been proposals (refer to, for example, Japanese Laid-Open Patent Publication No. 2006-254155).
Conventional relay stations perform amplification at all times even when there exists no mobile station in relay areas of the respective relay stations. This has raised problems in that the power consumption of the relay stations increases and in that a possibility of causing interferences of a cell with other cells occurs.